Chemiluminescent light production generally utilizes a two-component system to chemically generate light. Chemiluminescent light is produced by combining the two components, which are usually in the form of chemical solutions referred to as the “oxalate” component and the “activator” component. All suitable oxalate and activator compositions, inclusive of the various additional fluorescers, catalysts and the like, known to be useful in the prior art, are contemplated for use within the present invention.
The term “chemiluminescent reactant”, “chemiluminescently reactive” or “chemiluminescent reactant composition” is interpreted to mean a mixture or component thereof which will result in chemiluminescent light production when reacted with other necessary reactants in the processes as disclosed herein.
The term “fluorescent compound” is interpreted to mean a compound which fluoresces in a chemiluminescent reaction, or a compound which fluoresces in a chemiluminescent reaction.
The term “chemiluminescent composition” is interpreted to mean a mixture which will result in chemiluminescence.
The term “thixotropic composition” is interpreted to mean an admixture which behaves as a pseudo fluid when force is applied to it, but has properties of a solid when at rest.
The two components are kept physically separated prior to activation by a variety of means. Often, a sealed, frangible, glass vial containing one component is housed within an outer flexible container containing the other component. This outer container is sealed to contain both the second component and the filled, frangible vial. Forces created by intimate contact with the internal vial, e.g. by flexing, cause the vial to rupture, thereby releasing the first component, allowing the first and second components to mix and produce light. Since the objective of this type of device is to produce usable light output, the outer vessel is usually composed of a clear or translucent material, such as polyethylene or polypropylene, which permits the light produced by the chemiluminescent system to be transmitted through the vessel walls. These devices may be designed so as to transmit a variety of colors by either the addition of a dye or fluorescent compound to one or both of the chemiluminescent reactant compositions or to the vessel itself. Furthermore, the device may be modified so as to only transmit light from particularly chosen portions thereof.
It is desirable to produce chemiluminescent light from objects of various shapes or forms. U.S. Pat. No. 4,814,949 issued to Elliott discloses a means of making shaped, two-dimensional, chemiluminescent objects. Conventional liquid, chemiluminescent reagents are combined to produce light. A non-woven, absorbent article in the desired shape is permitted to absorb the chemiluminescent reagents after mixing and activation so that the article emits light from the shape desired. Although the shape may be as simple or as complex as desired, it is essentially limited to a two-dimensional surface and is additionally limited to producing a single color of light per device.
An example of creating a chemiluminescent system capable of producing light from a swellable polymeric composition is disclosed in U.S. Pat. No. 3,816,325 issued to Rauhut et al. Two primary means are employed to produce solid chemiluminescent systems. The first system relies on diffusion of a chemiluminescent oxalate solution into a solid polymer substrate such as a length of flexible vinyl tubing. The diffusion process occurs when a length of the vinyl tubing is immersed in a suitable chemiluminescent reagent for an extended period of time. After removal of the tubing from the oxalate solution, application of liquid activator to the surface of the tubing causes the tubing to emit light. Since the solid polymer is relatively non-porous, it is difficult to rapidly and completely activate the oxalate in the tubing because the relatively slow process of diffusion must also be relied upon to permit the activator solution to reach the chemiluminescent reagent diffused into the polymer before light can be generated.
In a further embodiment of U.S. Pat. No. 3,816,325, the chemiluminescent oxalate solution is mixed with a polyvinyl chloride (PVC) resin powder to form a paste, which is then spread on a substrate and baked in an oven to form a flexible, elastic film. While this embodiment is operative, the polyvinyl chloride sheet described exhibits weaknesses in uniformity, strength, flexibility, and most importantly, porosity. Additionally, the processes described are primarily suitable for producing relatively thin objects only and, extensive testing has determined that the formulations of '325 are entirely unsuitable for processes which may be desired to produce graphic patterns such as screen printing and coating applications. Additionally, there is no mention of using thixotropic compositions to produce graphic patterns. Further, there is no mention of using thixotropic chemiluminescent compositions to produce graphic patterns which are capable of producing light of various colors simultaneously.
U.S. Pat. No. 5,173,218 to Cohen et al. discloses a combination of PVC polymer resins to produce a porous, flexible, chemiluminescent structure from liquid slurries. Although an improvement in the art, the products produced still suffer from a variety of shortcomings, particularly if solid, chemiluminescent objects are to be produced which are other than relatively flat, thin objects. A thin “pad” is produced from a mixture of polymer resins, which is strong and flexible, and exhibits satisfactory absorptive properties of the activator fluid. However, the processes taught focus on producing pads which are made by pouring a liquid slurry mixture into molds. As such, the slurry and hence, the resulting pad shape, is limited to the shape of the mold, into which the slurry is poured and pools. Additionally, it is well-known to those skilled in the art that the formulas and processes utilized in the prior art may produce chemiluminescent pads with a relatively tough and impermeable “skin”-wherever the slurry has been in contact with the mold during the baking process. This skin is easily recognized as a darker and more transparent region of the pad and is highly impermeable. Consequently, it is incapable of rapidly absorbing liquid activator solution and as such, minimally contributes to light output of the device. The thickness of this skin varies with the time and temperature of the baking process, but in any event, this skin represents wasted material from which little usable light may be produced. It has been determined that this skin is created by an inability of the slurry to draw in air (or other gasses) during the baking process. To achieve a significantly porous product, air must enter the slurry mixture during the baking process from the exposed surfaces of the slurry pool. During the curing process, air is usually drawn into the pad to replace the volume occupied by solvents which become absorbed into the PVC resins. This process continues as air is drawn down to ever increasing depths within the pad as first the upper regions of the pad cure and then successively lower regions of the pad cure. It is this inclusion of air into the pad during the baking process which primarily determines the percent of open pore space and hence adsorptiveness of the pad. At some point during the baking process described, the bottom of the mold may reach a temperature at which the slurry mixture in contact with this region of the mold begins to jell and cure, even though an air path from the exposed surfaces of the slurry to this lower region may not have been created. Due to a lack of air available to this jelling slurry, this “bottom up” curing process results in a pad which is tough, dense, and virtually non-porous in the region of the pad proximal to the mold bottom and to a lesser extent, the mold edges. Certain adverse effects of this bottom up curing process can be minimized if the bottom of the mold is placed on a cold thermal mass in the curing oven, thereby providing for heating and curing of the bottom portion of the slurry following the remainder of the slurry. Nonetheless, the undesirable production of a tough and impermeable skin layer remains unaddressed. The process taught in '218 is an improvement over prior art but there is still no means taught to produce graphic patterns from the materials described in the '218 patent. Since the material employed to produce chemiluminescent pads in '218 is a pourable liquid, it must necessarily be cast into some sort of a mold or other containing means in order to produce any predetermined shaped pad. The mixtures taught in '218 are also entirely unsuitable for use in producing graphic patterns or any detail such as may be produced using screen printing processes and the like.
Another attempt to produce multi-colored chemiluminescent devices relies either on various optical filters or secondary fluorescers to alter the color of light produced in a liquid chemiluminescent system. Such attempts are unsatisfactory in that the number and quality of colors which may be filtered from light produced in a liquid chemiluminescent is very limited. Attempts at this often involve application of a colored decal or other filtering means to the outer surface of a conventional light stick. Other attempts at producing multi-colored chemiluminescent devices employing liquids rely on secondary fluorescers. Such fluorescers can for example, convert green light which is produced by a chemiluminescent reaction to red light. Stoke's law limits this conversion process to producing only those wavelengths of light which are lower than that of the original light. Additionally, these conversion processes are typically inefficient and waste significant amounts of optical energy. Further, the prior art fails to contemplate a product which may be independent of a container, and which is capable of generating a plurality of spatially separated colors or wavelengths of chemiluminescent light simultaneously over a planar surface.